Determine the effectiveness of I-131-LYM-1 as a salvage therapy in eliminating and reducing detectable tumor in subjects with intermediate to high-grade b-cell non-Hodgkin's lymphoma who are refractory to current firstline or salvage chemotherapy and to evaluate the safety of systemically administered I-131-LYM-1 in terms of incidence and severity of adverse reactions, human anti-mouse antibody (HAMA) development, and toxicity.